The present invention is generally in the field of laboratory handling of liquid specimens and more specifically concerns a multi-compartment plate capable of containing a plurality of liquid specimens and a method and system utilizing same.
Processing of liquid specimens to test a variety of parameters therein, is a standard endeavor in research as well as in day-to-day clinical diagnostics. In order to reduce costs and increase efficiency of such method, improved accuracy and eliminate sources for error, there is a growing tendency to develop and use automated systems in which a plurality of liquid specimens are simultaneously handled. One device common in most such methods is a plate comprising a plurality of liquid holding compartments in which the liquid specimens may be incubated.
A variety of methods involve filtering of the specimen through a filter medium, a medium following incubation, in order to view the retentate remaining on the filter. Prior art devices allowing simultaneous incubation and subsequent simultaneous filtration of a plurality of liquid specimens are multi-compartment plates where the bottom wall of the compartments is constituted by a filter. Such is the case, for example, in the device disclosed in U.S. Pat. Nos. 4,493,815, 5,047,215 and 5,223,133. The filter for which such an application has a small pore size, does not readily enable seepage of liquid therethrough and only upon the application of a vacuum, the liquid is forced to flow through the filter. However, there is always some absorbance of liquid specimen onto the filter sheet, which may be significant in case of small specimens. In addition, in long incubation processes, in particular in such involving agitation of the specimens, there may also be some leakage of liquid through the filters even without the application of the vacuum.
In devices where the filter is permanently attached to the bottom wall of the compartment, there is an inherent difficulty in viewing the retentate, as this has to be through the opening of the compartment, by the use of long field optics.
When using a filter medium removable from the bottom wall, there is a very serious problem of ensuring a firm, leakage-proof attachment of the filter to the bottom of the compartments, which is a difficult feat to achieve simultaneously for all the compartments in a plate.
The present invention has, as one of its objects, the provision of a novel device for simultaneous handling of a plurality of liquid specimens. It is particularly the object of the invention to provide such a device useful in procedures requiring filtration of the liquid specimens following incubation or any other treatment of the specimen within the compartment.
It is another object of the invention to provide a novel method for the simultaneous treatment of a plurality of liquid specimens and then filtering the specimens through a filter sheet for subsequent viewing of the retentate on the filter.
It is a further object of the invention to provide a novel system for simultaneous treatment of a plurality of liquid specimens and subsequent filtration of the specimens through a filter sheet.
Other objects of the invention will be clarified from reading of the following text.
The present invention provides, by a first of its aspects, a device in the form of a plate comprising a plurality of compartments, each compartment being adapted to hold a liquid specimen and having an aperture at its top for introducing and withdrawing liquid into and from the compartment, respectively; each compartment has a vent opening at a side wall at about mid portion thereof between the compartment""s top and bottom.
The present invention provides a filter device for filtering specimens contained in a multi-compartmental plate comprising a planar body with a top and a bottom face, having a plurality of openings, and a filter sheet stretched to cover all openings, the device being attachable to said plate at its top face with each opening being in register with and attached to an aperture of one compartment, such that the filter is stretched over said aperture to allow vacuum filtration of specimens from the compartments through the filter.
In accordance with a preferred embodiment, the filter sheet is stretched over said bottom face. In accordance with another preferred embodiment, said filter device cooperates with a support member attached to the bottom face of the filter device for supporting the filter during the vacuum filtration. Typically the filter sheet is stretched by cooperation stretching members in such filter device and in said support member, e.g. projections in one and recesses in the other for receiving the projections.
In accordance with another aspect of the invention there is provided a method for processing a plurality of liquid specimens, comprising:
(a) providing a multi-compartmental plate which comprises a plurality of compartments each adapted to hold a liquid specimen and having an aperture at its top for introducing or removing of liquid and a vent opening within the compartment at a mid-portion thereof;
(b) introducing each one of the plurality of liquid specimens into one of the plate""s compartments;
(c) treating or incubating the specimens contained in the compartments;
(d) attaching a filter sheet to the plate such that it covers the openings of the compartments and propelling the liquid through the filter sheet; and
(e) separating the filter sheet from the plate and viewing particulate retentate remaining on the filter sheet.
A further aspect of the present invention is concerned with a system for simultaneous processing of a plurality of liquid specimens, comprising:
i. a multi-compartmental plate as defined above;
ii. a filtration assembly comprising a filter device as defined above, and preferably also said support device.
A unique feature of the multi-compartmental plate, the method or system of the invention is in that the filter sheet is attached to the plate only at the end of the specimen""s treatment process, just prior to filtration. Thus, in accordance with the invention there is no contact between the filter sheet and the liquid specimen until that stage.
A particular preferred application of the invention is in the field of assaying liquid specimens, both in research and in clinical diagnostics, in order to qualify or quantify the presence, type or characteristics of living matter contained therein, e.g. to diagnose microorganismal infection in a body fluid.
The invention will now be illustrated, by way of example only, by some non-limiting specific embodiments, with reference to the annexed drawings.